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Daubentonia madagascariensisaye-aye

By Elizabeth Boucher

Geographic Range

Daubentonia madagascariensis, commonly known as the aye-aye, is endemic to Madagascar. Aye-ayes can be found widely distributed across the island. (Quinn and Wilson, 2004)

Habitat

Daubentonia madagascariensis can be found in a wide variety of environments including primary and secondary rainforest, deciduous forest, cultivated plantations, and occasionally dry scrub forest and mangrove forest. They spend most of their time in the upper two levels of the canopy. (Ancrenaz, et al., 1994; Quinn and Wilson, 2004)

Physical Description

Aye-ayes have a head-body length from 360 to 440 mm and a long bushy tail. The coat is long, coarse, and either dark brown or black in color, with scattered white guard hairs. The face and throat are pale gray and facial features include yellow-orange or sandy brown eyes surrounded by dark markings, large triangular ears, a short snout, and a pink nose. There is no significant sexual dimorphism between males and females. (Feistner, et al., 1995; Quinn and Wilson, 2004; Soligo, 2005)

Aye-ayes have highly specialized digits. The third digit of the hand is slender, elongated, and flexible, and is especially important in feeding behaviors. Aye-ayes have a dental formula of I:1/1, C:0/0, PM:1/0, M:3/3. The incisors are large and ever-growing, with enamel coating only the anterior surface. There is a large diastema present in both the upper and lower jaws. (Feistner, et al., 1995; Quinn and Wilson, 2004; Soligo, 2005)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    2570 to 2615 g
    90.57 to 92.16 oz
  • Range length
    360 to 440 mm
    14.17 to 17.32 in

Reproduction

During each mating cycle females typically mate with more than one male, representing a multi-male, multi-female mating system. (Quinn and Wilson, 2004)

Aye-ayes have an extended mating season. Observations in the wild showed a five month period from October to February when individuals were mating, or there were visible signs of females in estrus. Female estrous cycles range from 21 to 65 days and are characterized by changes in the vulva, which is usually small and gray, and becomes large and red during these cycles.

There is a gestation period of 152 to 172 days, and infants are typically born between February and September. There is a 2 to 3 year interval between births. This long interbirth interval may be due to the relatively slow development of young and high levels of parental investment.

Aye-ayes have an average neonatal weight of 90 to 140g and will grow to be roughly 2615 g for males and 2570 g for females. Infants have a coat that is similar in color to adults, but they are distinguished in appearance by their green eyes and floppy ears. Infants also have a deciduous dental formula of: I:1-2/1-2, C1/1, PM:2/2. This deciduous dentition is shed at 20 weeks. (AnkelSimons, 1996; Feistner and Ashbourne, 1994; Feistner, et al., 1995; Quinn and Wilson, 2004)

  • Breeding interval
    Female aye-ayes give birth every 2 to 3 years.
  • Breeding season
    Mating occurs from October to February.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    152 to 172 days
  • Range weaning age
    20 (high) weeks
  • Average age at sexual or reproductive maturity (female)
    2.5 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    882 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    2.5 years

Aye-ayes have a relatively slow rate of development, compared to other Strepsirrhini. Observations of this species in the first year of development showed that young first left the nest at 8 weeks. They began feeding on solid food regularly at 20 weeks, the same time that the deciduous dentition is lost, and were still food begging and making attempts to suckle at one year old. This extended period of dependence is probably related to their highly specialized feeding behaviors. Young aye-ayes typically achieve adult proficiency in locomotion by 9 months and reach sexual maturity by 2.5 years. (Feistner and Ashbourne, 1994; Quinn and Wilson, 2004)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • extended period of juvenile learning

Lifespan/Longevity

A captive female lived to an age of 23.3 years. (de Magalhães, 2007)

Behavior

Aye-ayes are nocturnal and solitary. Most of the daytime is spent sleeping in an ovular nest located in the upper two levels of the canopy. Individuals tend to sleep singly, but may share a nest on occasion, and nests can be occupied by different individuals at different times. Activity begins half an hour before sunset and continues to 3 hours after sunset. Males usually become active before females. During the night, aye-ayes spend their time alternately foraging, feeding, and grooming. Aye-ayes may assemble in foraging parties of 2-3 individuals. Aye-ayes often cling upside down on branches and can rest vertically or horizontally. (Ancrenaz, et al., 1994; Krauker, et al., 2002; Quinn and Wilson, 2004)

Aye-ayes are able to make use of a wide range of locomotor methods including arboreal quadrupedalism, leaping, and head-first descent. The forces of locomotion can be potentially harmful to the long, slender digits of the aye-aye, so individuals may curl their fingers or shift their bodies to carry more weight caudally. These techniques help prevent damage to their delicate fingers. The powerful, opposable big toe, robust shoulder girdle, and strong humerus are features that help enable head-first descent. Aye-ayes are able to use wide and narrow, as well as vertical, horizontal, and oblique branches as supports in locomotion. (Ancrenaz, et al., 1994; Krauker, et al., 2002; Quinn and Wilson, 2004)

Home Range

Individuals have their own ranges, which are scent marked and possibly marked by distinctive tooth impressions made by powerfully biting into tree bark. Male ranges are larger than female ranges, and each male range overlaps with at least one female range. Furthermore, male ranges overlap between 40 and 75 percent, and these shared spaces may be occupied by numerous individuals simultaneously. Female home ranges are from 30 to 40 hectares in area, while male home ranges are from 125 to 215 hectares. (Ancrenaz, et al., 1994; Mittermeier, et al., 2006; Quinn and Wilson, 2004)

Communication and Perception

Aye-ayes communicate using a number of vocalizations. A distinctive scream indicates aggression, and a closed mouth version of this scream can indicate protest. A brief descending whimper is heard in connection with competition over food resources. A “tiss” sound serves as a response to the appearance of humans or lemurs, and a “hai-hai” vocalization can be heard during attempts to flee from captors. (Quinn and Wilson, 2004)

Food Habits

To fulfill basic needs for growth and maintenance, aye-ayes require a diet rich in fats and proteins. In the wild roughly 240 to 342 kilocalories are consumed daily and the calorie intake is steady throughout the year, although it is slightly lower in the cold season relative to the hot, wet, and dry seasons. Aye-ayes have a varied diet consisting of fruits, nuts, and plant exudates. Breadfruit, banana, coconuts, and ramy nuts are among the favored foods, but bamboo, nectar from the traveler’s tree, lychees, and mangoes may also be consumed. Aye-ayes use their specialized third digit to pierce the outer skin of fruits and scoop out the contents. (Dierenfeld, et al., 1994; Erickson, et al., 1998; Erickson, 1995; Kaufman, et al., 2005; Quinn and Wilson, 2004)

Xylophagous, or wood boring, insect larvae make up another important component of the aye-aye diet, especially cerambycid beetle larvae. Aye-ayes have several derived features and a unique percussive foraging method to detect the presence of these larvae in trees. The specialized third digit is used to tap on wood in search of hollow spaces below the surface of the bark. There are conflicting views on whether aye-ayes can detect the sound of reverberations in these cavities or whether they can detect breaks in the integrity of the wood. Once a cavity is found, the aye-aye uses its large, procumbent incisors to gnaw through the bark and extracts the larvae with its long and slender third digit. There are several other features that may be related to foraging behaviors. These include an enlarged frontal cortex and an increased volume of the olfactory lobe, as well as large, naked ears, which enhance hearing. (Dierenfeld, et al., 1994; Erickson, et al., 1998; Erickson, 1995; Kaufman, et al., 2005; Quinn and Wilson, 2004)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • nectar
  • sap or other plant fluids

Predation

Aye-ayes may be prey for fossas, Cryptoprocta ferox, one of Madagascar’s largest carnivores. However, little is known about predation on aye-ayes. Their nocturnal and arboreal habits may protect them from much predation. (Quinn and Wilson, 2004)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Aye-ayes may help to disperse fruiting tree seeds through their frugivory. They are also important predators of wood-boring beetle larvae.

Economic Importance for Humans: Positive

Aye-ayes are fascinating animals that are important members of native Malagasy ecosystems.

Economic Importance for Humans: Negative

Aye-ayes may inhabit cultivated areas and farmlands, including coconut and lychee plantations. As a result, they are sometimes considered crop pests. (Quinn and Wilson, 2004)

  • Negative Impacts
  • crop pest

Conservation Status

Daubentonia madagascariensis has been listed as an endangered species since the 1970s. In 1992 the IUCN estimated the total population to be between 1,000 and 10,000 individuals. The rapid loss of their natural habitat due to encroachment by humans is the main threat to this species. In addition, aye-ayes are hunted or killed on the spot by native Malagasy who see them as crop pests or bad omens. Currently, aye-ayes can be found in at least 16 protected areas across Madagascar. There is an effort to develop breeding colonies of captive aye-ayes. (Quinn and Wilson, 2004)

Other Comments

Daubentonia madagascariensis is the only extant member of the family Daubentoniidae. Fossils of a late Holocene species known as Daubentonia robusta have been recovered, which was about 30 percent larger than aye-ayes.

The common name "aye-aye" may be derived from the “hai-hai” vocalization they make while fleeing from their nests. (Quinn and Wilson, 2004)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Elizabeth Boucher (author), Yale University, Eric Sargis (editor, instructor), Yale University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Ancrenaz, M., I. Lackamancrenaz, N. Mundy. 1994. Field Observations of Aye-Ayes. Folia Primatologica, vol. 62 issue 1-3: 22-36.

AnkelSimons, F. 1996. Deciduous Dentition of the Aye-Aye. American Journal of Primatology, vol. 39 issue 2: 87-97.

Dierenfeld, E., C. Ashbourne, A. Feistner. 1994. Dietary-intake, Food Composition and Nutrient Intake in Wild and Captive Aye-Ayes. Folia Primatologica, vol. 62 issue 1-3: 115-124.

Erickson, C. 1995. Feeding Sites for Extractive Foragaing by the Aye-Aye. American Journal of Primatology, vol. 35 issue 3: 235-240.

Erickson, C., S. Nowiki, L. Dollar, N. Goehring. 1998. Precursive Foraging: Stimuli for Prey Location by Aye-Ayes. International Journal of Primatology, vol. 19 issue 1: 111-122.

Feistner, A., C. Ashbourne. 1994. Infant Development in a Captive Bred Aye-Aye. Folia Primatologica, vol. 62 issue 1-3: 74-92.

Feistner, A., E. Sterling, Dodo. 1995. Body Mass and Sexual Dimoorphism in the Aye-Aye. Journal of the Wildlife Preservation Trusts, vol. 31: 73-76.

Kaufman, J., E. Ahrens, D. Laidlaw. 2005. Anatomical Analysis of an Aye-Aye Brain Combining History, Structural Magnetic Resonance Imanging and Diffusion-Tensor Imaging. Anatomical Record, vol. 287A issue 1: 1026-1037.

Krauker, J., P. Lemlin, D. Schmidt. 2002. Hand and Body Position During Locomotor Behavior in the Aye-Aye. American Journal of Primatology, vol. 57 issue 3: 105-118.

Mittermeier, R., W. Konstant, F. Hawkins, E. Louis, O. Langrand, J. Ratsimbazafy, R. Rasoloarison, J. Ganzhorn, S. Rajaobelina, I. Tattersall, D. Meyers. 2006. Lemurs of Madagascar. Colombia: Conservation International, Tropical Field Guide Series.

Quinn, A., D. Wilson. 2004. Daubentonia madagascariensis. Mammalian Species, vol. 710: 1-6.

Soligo, C. 2005. Anatomy of the Hand and Arm in Daubentonia Madagascariensis. Folia Primatologica, vol. 76 issue 5: 262-300.

de Magalhães, J. 2007. "Daubentonia madagascariensis" (On-line). AnAge: The Animal Ageing Resource. Accessed December 18, 2007 at ttp://www.genomics.senescence.info/species/entry.php?species=Daubentonia_madagascariensis.

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